In January 2017, a retired satellite reentered the atmosphere—an old soldier that undoubtedly had provided many years of good service. Hopefully, in some secure vault somewhere, the organization that flew it had a ceremony where they honored the memory of their departed friend. This was certainly a US satellite that had been tracked and monitored up until the end, but this one was an “off the books” satellite.

However, somewhere in the world, someone might have seen a satellite reenter and wondered what it was. The good news in this case is that those people would have been sailing in the South Pacific, far from land. But if the US knew that the satellite was about to reenter, shouldn’t our country have notified someone? Unannounced reentries have happened before and will happen again, but many of them could be announced with no loss. Each reentry incurs risk, which the US government has decided that it would accept. But is there a reason to accept any risk in these cases?